1. Field of the Invention
The present invention relates to a start control device for a vehicle and a method for controlling the start control device for a vehicle. In particular, the present invention relates to a start control device for a vehicle in which a cranking hold control operation is performed and a method for controlling the start control device for a vehicle.
2. Description of the Related Art
A start control device for a vehicle is generally known which, when the driver carries out a starting operation, performs a cranking hold control operation including the steps of supplying electric power to a starter motor to cause it to start cranking of the engine and continuing the cranking until the engine rotational speed reaches a predetermined rotational speed for use in determining whether or not the engine has achieved complete combustion (hereinafter, called “complete combustion determination rotational speed”) in order to improve the starting performance of the engine.
Conventionally, in a vehicle provided with this type of a start control device for a vehicle, the starting operation is usually carried out using a push-type start button (which is hereinafter referred to simply as “start button”), and the cranking hold control operation as described above is performed when the start button is pressed.
As one start control device for a vehicle which determines whether or not complete combustion has been achieved based on a predetermined complete combustion determination rotational speed, a start control device is disclosed having; cranking determination means for determining whether or not the engine is being cranked; complete combustion determination means for determining whether or not the engine has achieved complete combustion; engine temperature detection means for detecting engine coolant temperature; engine rotational speed detection means for detecting engine rotational speed; basic injection amount determination means for determining a basic starting fuel injection amount based on the detected engine coolant temperature and engine rotational speed; and reduction control means for reducing the basic starting fuel injection amount with time from the time when the cranking determination means determines that the cranking has been completed until the complete combustion determination means determines that the engine has achieved complete combustion, in which the complete combustion determination means determines that the engine has achieved complete combustion when the engine rotational speed reaches a predetermined complete combustion determination rotational speed, and in which a larger value is set as the predetermined complete combustion determination rotational speed as the engine coolant temperature is lower (see Japanese Patent Application Publication No. 2001-173490 (P-A-2001-173490), for example).
The start control device for a vehicle disclosed in JP-A-2001-173490 has previously stored a coolant temperature map showing the relation between the engine coolant temperature and the predetermined complete combustion determination rotational speed, and determines a complete combustion determination rotational speed based on the coolant temperature map. Therefore, it can determine whether or not complete combustion has been achieved properly based on the engine coolant temperature at the start of the engine.
However, since different engines have different complete combustion characteristics, the conventional start control device for a vehicle as described above requires a coolant temperature map including complete combustion determination rotational speeds determined for the engine coolant temperatures under the conditions suitable for the complete combustion characteristics of the engine. Therefore, different start control devices are developed for different types of engines. Thus, a large number of development staff and a long developing time are required, resulting in an increase in development costs. Also, since different start control devices developed for different engines require different quality maintenance approaches, the workload of quality inspection places a heavy burden on the inspection staff.